Is money earned from working in a restaurant that serves pork, without eating or selling it, forbidden, and are the cited proofs for the permissibility of benefiting from impure substances, other than by eating them, sound?

It is not permissible to work in cooking pork or anything into which it has entered, because it is not permissible to consume it, nor to aid in its consumption.

What has been attributed to the Hanafi madhhab (definition) is not their position on the issue, for they do not permit the sale of intrinsically impure substances, but rather the sale of substances that have become impure.

The Hanbalis and Hanafis have agreed on the impermissibility of using impure oil for lighting, citing the saying of the Prophet, peace be upon him: "Indeed, Allah and His Messenger have forbidden the sale of alcoholic beverages, dead animals, pigs, and idols."

The hadith (definition) about the mouse pertains to the permissibility of using that which has become impure, not that which is intrinsically impure. The hadith of Maymuna cannot be analogized to what has been mentioned due to the difference between a pig and a sheep.

Therefore, you must refrain from manufacturing anything into which pork enters. If you cannot do so, then you must leave this work, based on the words of Allah Almighty: {And cooperate in righteousness and piety, but do not cooperate in sin and aggression.}

As for Hajj and 'Umrah (definition) with money earned from this work, the money is mixed. The money used for Hajj or 'Umrah can be accounted for from the permissible money, keeping in mind that Hajj performed with illicit money is valid, though sinful.